Is preoperative radiographic localization of islet cell tumors in patients with insulinoma necessary?

A comparison of three (67/68)Ga-labelled exendin-4 derivatives for β-cell imaging on the GLP-1 receptor: the influence of the conjugation site of NODAGA as chelator

Background

Various diseases derive from pathologically altered β-cells. Their function can be increased, leading to hyperinsulinism, or decreased, resulting in diabetes. Non-invasive imaging of the β-cell-specific glucagon-like peptide receptor-1 (GLP-1R) would allow the assessment of both β-cell mass and derived tumours, potentially improving the diagnosis of various conditions. We tested three new ^67/68Ga-labelled derivatives of exendin-4, an agonist of GLP-1R, in vitro and in vivo. We determined the influence of the chelator NODAGA conjugated to resident lysines either at positions 12 and 27 or the C-terminally attached lysine at position 40 on the binding and kinetics of the peptide.

Methods

Binding and internalisation of ⁶⁷Ga-labelled Ex4NOD12, Ex4NOD27 and Ex4NOD40 were tested on Chinese hamster lung (CHL) cells stably transfected to express the GLP-1 receptor (GLP-1R). In vivo biodistribution of ⁶⁸Ga-labelled peptides was investigated in CD1 nu/nu mice with subcutaneous CHL-GLP-1R positive tumours; the specificity of the binding to GLP-1R was determined by pre-injecting excess peptide.

Results

All peptides showed good in vitro binding affinities to GLP-1R in the range of 29 to 54 nM. ^67/68Ga-Ex4NOD40 and ^67/68Ga-Ex4NOD12 show excellent internalisation (>30%) and high specific uptake in GLP-1R positive tissue, but high activity was also found in the kidneys.

Conclusions

We show that of the three peptides, Ga-Ex4NOD40 and Ga-Ex4NOD12 demonstrate the most favourable in vitro properties and in vivo binding to GLP-1R positive tissue. Therefore, we conclude that the lysines at positions 12 and 40 might preferentially be utilised for modifying exendin-4.

Imaging of neuroendocrine tumors

Neuroendocrine tumors (NETs) constitute a large group of diverse neoplasms with a wide spectrum of clinical, imaging, and pathologic findings. Imaging diagnosis of NETs can be challenging, and several complementary imaging modalities may be needed during the diagnostic workup. Accurate interpretation of the imaging findings is important to facilitate diagnosis and contribute to patient management. This article discusses the gastrointestinal site-specific features and the tumor-specific features of several NETs and the role of several imaging modalities such as computed tomography, MR imaging, ultrasonography, and positron emission tomography in the evaluation of these NETs.

Usefulness of EUS combined with contrast-enhancement in the differential diagnosis of malignant versus benign and preoperative localization of pancreatic endocrine tumors

BACKGROUND

Pancreatic endocrine tumors (PETs) develop in relatively few patients, but they are often difficult to diagnose because of their small size and various clinical symptoms.

OBJECTIVE

The aim of this study was to investigate the usefulness of EUS combined with contrast enhancement (CE-EUS) in the preoperative localization of PETs and the differentiation between malignant and benign PETs.

DESIGN AND SETTING

Single-center retrospective study.

PATIENTS

Sixty-two pathologically certified PETs of 41 patients who underwent EUS, multiphasic multidetector computed tomography (MDCT), and transabdominal US at our institute since 2001.

INTERVENTIONS

Intravenous injection of US contrast media.

MAIN OUTCOME MEASUREMENTS

Comparison of EUS, MDCT, and US in the preoperative identification of PETs, and the characteristic findings of EUS with malignancy.

RESULTS

EUS showed high sensitivity (95.1%) in identifying PETs compared with MDCT (80.6%) and US (45.2%). Multivariable logistic regression analysis showed that heterogeneous ultrasonographic texture was the most significant factor for malignancy (OR = 53.33; 95% CI, 10.79-263.58). Most heterogeneous hypoechoic areas and anechoic areas corresponded to hemorrhage or necrosis on pathologic examination. They were identified as filling defects in CE-EUS and were more clearly recognized than in conventional EUS.

LIMITATIONS

Retrospective study.

CONCLUSION

EUS has higher sensitivity in preoperative localization of PETs compared with MDCT and US. The characteristics of EUS and CE-EUS findings in malignant PETs were clarified, and they will improve the diagnostic accuracy of PETs.

[Invasive diagnostic procedures for insulinomas of the pancreas]

Insulinomas are the most common cause for hypoglycemia with endogenous hyperinsulinism. Insulinomas are the most frequent endocrine tumor of the pancreas and 10% occur as multiple tumors (e.g. multiple endocrine neoplasia type I) or in rare cases as islet cell hyperplasia. A further 10-15% of insulinomas are malignant. Non-invasive imaging modalities, such as computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography (US) and somatoreceptor scintigraphy (SRN) show a lower sensitivity for detection and localization of tumors, because in many cases insulinomas are smaller than 2 cm in size. Invasive pre-operative diagnostic procedures, such as transhepatic peripancreatic venous blood sampling (TPVB) and the intra-arterial calcium stimulation test (ASVS) are much more time-intensive compared to CT, MRI and US with an examination time of 2-3 h but achieve a more exact pre-operative detection and localization with sensitivities mostly greater than 95% and are therefore the diagnostic methods of choice.

Neuroendocrine tumors of the pancreas

Pancreatic endocrine tumors are rare neoplasms accounting for less than 5% of pancreatic malignancies. They are broadly classified into either functioning tumors (insulinomas, gastrinomas, glucagonomas, VIPomas, and somatostatinomas) or nonfunctioning tumors. The diagnosis of these tumors is difficult and requires a careful history and examination combined with laboratory tests and radiologic imaging. Signs and symptoms are usually related to hormone hypersecretion in the case of functioning tumors and to tumor size or metastases with nonfunctioning tumors. Surgical resection remains the treatment of choice even in the face of metastatic disease. Further development of novel diagnostic and treatment modalities offers potential to greatly improve quality of life and prolong disease-free survival for patients with pancreatic endocrine tumors.

Laparoscopic surgery for pancreatic insulinomas: a single-institution experience of 29 cases

BACKGROUND

Laparoscopic approach has been increasingly used in the treatment of pancreatic benign diseases. This report evaluates our experience with laparoscopic surgery for pancreatic insulinomas.

METHODS

Between July 2000 and December 2007, laparoscopic pancreatectomy was attempted in 29 consecutive patients with insulinomas. The localization of tumors, operating characteristics, and clinical outcomes were analyzed.

RESULTS

Tumors were precisely localized in 28 of 29 (96.6%) patients by a combination of preoperative imaging techniques and intraoperative ultrasonography. Laparoscopic pancreatectomy was successfully performed in 26 patients, including enucleation (n = 14), hand-assisted enucleation (n = 2), and distal pancreatectomy with (n = 9) or without (n = 1) spleen preservation. Two conversions to open procedure were required because of unfavorable locations of the tumors. The pancreatic fistula occurred in four patients who underwent tumor enucleation. The median hospital stay was 5.5 days (range, 3-18 days) after laparoscopic procedure. Twenty-eight patients with pancreatic resection were free of symptoms and remained normoglycemic after a median follow-up period of 19 months (range, 10-36 months).

CONCLUSION

Laparoscopic pancreatic resection is a feasible and safe procedure for patients with insulinomas. Further studies are required to evaluate the potential application of the hand-assisted approach for tumors located at anatomically unfavorable positions.

Laparoscopic management of insulinomas

BACKGROUND

Conventional surgical management of insulinomas involves an open technique. The laparoscopic approach has advantages in terms of improved postoperative pain and recovery time. This retrospective study evaluated the laparoscopic management of pancreatic insulinomas.

METHODS

Between December 2000 and March 2007, 23 patients were referred for consideration of laparoscopic insulinoma resection. Two patients were not deemed appropriate for the laparoscopic approach and were managed with open surgery. All surgery was performed by one experienced pancreatic surgeon. Laparoscopic intraoperative ultrasonography was not available for the first six procedures, but was used thereafter.

RESULTS

Twenty-one patients (five men and 16 women, median age 46 (range 22-70) years) had a successful resection. All had single tumours, five in the head, nine in the body and seven in the tail of the pancreas. One conversion to open operation was performed in a patient with an insulinoma in the head of the pancreas who had dense adhesions resulting from pancreatitis. Three patients developed a postoperative pancreatic fistula. There has been no recurrence of symptoms in any patient.

CONCLUSION

Laparoscopic management of insulinomas is feasible and safe. Laparoscopic intraoperative ultrasonography is a promising adjunct to the procedure, even after accurate preoperative localization.

Celiac artery stenosis/occlusion treated by interventional radiology

Severe stenosis/occlusion of the proximal celiac trunk due to median arcuate ligament compression (MALC), arteriosclerosis, pancreatitis, tumor invasion, and celiac axis agenesis has been reported. However, clinically significant ischemic bowel disease attributable to celiac axis stenosis/occlusion appears to be rare because the superior mesenteric artery (SMA) provides for rich collateral circulation. In patients with celiac axis stenosis/occlusion, the most important and frequently encountered collateral vessels from the SMA are the pancreaticoduodenal arcades. Patients with celiac artery stenosis/occlusion are treated by interventional radiology (IR) via dilation of the pancreaticoduodenal arcade. In patients with dilation of the pancreaticoduodenal arcade on SMA angiograms, IR through this artery may be successful. Here we provide several tips on surmounting these difficulties in IR including transcatheter arterial chemoembolization for hepatocellular carcinoma, an implantable port system for hepatic arterial infusion chemotherapy to treat metastatic liver tumors, coil embolization of pancreaticoduodenal artery aneurysms, and arterial stimulation test with venous sampling for insulinomas.

Pancreatic neuroendocrine tumours

Pancreatic neuroendocrine tumours (PET) are rare neoplasms of the pancreas accounting for less than 5% of all primary pancreatic malignancies. Included in this group are insulinomas, gastrinomas, glucagonoma and somatostatinomas. Collectively these neoplasms are classified as functional PETs. Where a PET is not associated with a clinical syndrome due to hormone oversecretion, it is referred to as a non-functioning PET. Non-functioning PETs are pancreatic tumours with endocrine differentiation but lack a clinical syndrome of hormone hypersecretion. The incidence of these tumours varied between 15 and 53%. Presentation is related to the mass effect of the tumour with symptoms often non-specific. Treatment is surgical excision with chemotherapy and hormonal therapy is controversial. For functioning PETs, surgery remains the optimal therapy, however, long-term survival can be expected even in the presence of metastases. With advances in medical management, radiolabelled somatostatin therapy, hepatic arterial chemoembolisation and radiofrequency ablation, symptoms may be controlled to optimize quality of life.

Surgical approach to insulinomas: are pre-operative localisation tests necessary?

INTRODUCTION

Insulinoma is a rare, but curable, endocrine tumour. The ability to localise the tumour accurately before or during surgery is an important factor in the management of these elusive lesions, which has been extensively debated. We have reviewed our experience of these lesions to establish the role of localisation tests.

PATIENTS AND METHODS

The medical records of 20 consecutive patients who had surgery for sporadic insulinomas since 1985 at this institution were retrospectively reviewed. All the patients had a definite biochemical diagnosis of endogenous hyperinsulinism. Results of pre-operative and intra-operative localisation tests were compared with the final outcome.

RESULTS

Of the 20 patients with sporadic insulinomas reviewed, 17 patients (85%) had multiple pre-operative localising investigations. Overall accuracy of pre-operative localisation tests was 33%. Non-invasive pre-operative localisation tests (ultra-sonography, CT, MRI) had a combined localisation rate of 25% with MRI having the highest sensitivity of 71%. Invasive tests (angiography, transhepatic portal venous sampling [THPVS], endoscopic ultrasound) detected 48% of lesions with THPVS being most sensitive (67%). THPVS was particularly helpful in localising lesions before re-operation. Intra-operative inspection and palpation localised the lesions correctly in 91% and intra-operative ultrasound in 93% of cases. All 5 occult tumours (indeterminate anatomical site before operation) were palpable at surgery and four of these were also correctly identified by intra-operative ultrasound. Site and size of tumour correlated poorly with pre-operative localisation. Operative procedure did not influence outcome with three patients needing re-operation. One patient died (5% mortality) and 9 patients (45%) had complications. Normoglycaemia has been obtained in all but one patient.

CONCLUSIONS

Insulinomas can be readily localised by systematic operative exploration. Non-invasive pre-operative investigations (ultrasonography/MRI) may help identify the location of tumour to determine the appropriate surgical procedure. Invasive pre-operative localisation tests like angiography and THPVS may be a valuable adjunct for re-operations. This also helps reduce the costs.

Surgical treatment of persistent hyperinsulinemic hypoglycemia (PHH) (insulinoma and nesidioblastosis)

BACKGROUND

The persistent hyperinsulinemic hypoglycemia is characterized by clinical symptoms that occur when the blood glucose levels drop below the normal range. Two pathological situations cause this clinical problem: The presence of a tumor of the pancreas secreting excessive amounts of insulin, known as insulinoma, and congenital beta-cell hyperplasia in the pancreas in children and noninsulinoma pancreatogenic hypoglycemia syndrome in adults.

PATIENTS AND METHODS

Clinical characteristic and surgical outcome of a group of 20 patients operated on for this hypoglycemic syndrome; 18 for insulinoma and two for nesidioblastosis in children was studied.

RESULTS

eight of the insulinomas were in the head of the pancreas, two in the body, and the remaining eight in the tail. The surgical technique was enucleation in nine cases, local resection in one case because of suspicious malignancy, and distal pancreatectomy in eight cases. Both children with nesidioblastosis underwent 85% pancreatectomy with splenic preservation. There was no mortality in the study, but three patients developed a low-volume pancreatic fistula after head enucleation.

CONCLUSIONS

Negative results in diagnostic localization together with the small size of the insulinoma represent a poor combination for successful surgery. The intraoperative ultrasonography is the method of choice for the identification of the tumor, as it is able to identify nonpalpable lesions.

Neuroendocrine tumors of the pancreas, excluding gastrinoma

In summary, neuroendocrine tumors of the pancreas comprise a unique and relatively rare group of tumors, of which gastrinoma and insulinoma are the most common types. Insulinomas tend to be small, solitary and benign, with surgical resection curable in most cases. The remainder of the neuroendocrine tumors are usually large, and unlikely to be cured with surgery; their slow-growing nature, however, mandates aggressive surgical therapy; even in cases where metastatic disease is present. Somatostatin analogs such as octreotide, are used to control the symptoms of hormone secretion; they are generally less effective in patients with insulinoma than in those with the other neuroendocrine tumors. Streptozocin, 5-fluorouracil, and doxorubicin are the most widely used chemotherapeutic agents in metastatic neuroendocrine tumors; their efficacy is limited, and significant side effects limit their use. Finally, liver transplantation in very select patients may prolong survival and alleviate debilitating symptoms.

[Pancreatic insulinomas]

Insulinoma is the most frequent neuroendocrine pancreatic tumor. In the present study, the clinical and immunohistochemical results of 20 patients who underwent surgery between January 1986 and December 2004 were evaluated. Clinical presentation, laboratory data, imaging studies, aspects of the surgical technique, complication rates and medium- and long-term follow-up were analyzed. Surgical treatment was recommended in all patients based on presenting symptoms and laboratory signs of hypoglycemia and hyperinsulinemia. In 15 patients, the lesion was identified preoperatively. In the 5 remaining patients, intraoperative palpation and ultrasonography were used to locate the lesion. The most frequently performed surgical procedures were pancreatic resection in 10 patients and laparotomic enucleation in the remaining 10. Laparoscopy was used in two patients. Two patients developed diabetes mellitus. The most frequent surgical complication was pancreatic fistula. No mortality was observed in the present series. Symptom reversion, characterized by disappearance of Whipple's triad and normal or increased glycemia values compared with preoperative values, was observed in all patients.

Laparoscopic Management of Insulinoma in a Child with Multiple Endocrine Neoplasia Type 1

The diagnosis and surgical management of insulinomas associated with multiple endocrine neoplasia type 1 (MEN1) pose additional problems in children because of the long-term risk of recurrence of other pancreatic and non-pancreatic tumors. We report a diagnostic confirmation by laparoscopic ultrasound of an insulinoma and its successful removal by laparoscopic enucleation in an 8- year-old boy who was admitted to our hospital with a history of recurrent episodes of absences, headache, and visual and auditive disturbances diagnosed as hyperinsulinism-related hypoglycemia. Magnetic resonance imaging of the pancreas showed a small contrast-enhancing lesion in the body of the pancreas, suspected for insulinoma. MEN1 was genetically proven by direct DNA testing. A pancreatic tumor can arise before the age of 10 in patients with MEN1 and can be surgically treated by a laparoscopical approach.

Laparoscopic surgery in patients with sporadic and multiple insulinomas associated with multiple endocrine neoplasia type 1

There have recently been reports of a limited number of laparoscopic procedures in patients with clinically manifest hyperinsulinism. However, the precise role of laparoscopy remains unknown. Between January 1998 and September 2003, 11 consecutive patients (10 women and 1 man; mean age, 40 years; age range, 22-66 years) with sporadic insulinoma and two female patients (25 and 40 years old) with multiple insulinomas associated with multiple endocrine neoplasia type 1 (MEN-1) were operated on using the laparoscopic approach. Endoscopic ultrasonography was used to localize the tumor preoperatively in 90% of patients with sporadic insulinoma. In patients with MEN-1, computed tomography and octreoscan-(111)In demonstrated multiple tumors. Laparoscopic ultrasonography (LapUS) was performed in all patients for operative decision-making. Of 11 patients with sporadic insulinoma, laparoscopic enucleation (LapEn) was planned in 8 patients, but in 1 patient, the use of LapUS missed the tumor and the patient was converted to open surgery. Mean operating time after LapEn (seven patients) was 180 minutes, and the mean blood loss was 200 ml. The mean hospital stay was 5 days. In three of the 11 patients, laparoscopic spleen-preserving distal pancreatectomy (LapSPDP) was performed; the mean operative time was 240 minutes, and the mean blood loss was 360 ml. Postoperative complications occurred in three of seven patients after LapEn (three pancreatic fistulas managed conservatively, and one case of bleeding requiring reoperation). LapSPDP was performed in both patients with MEN-1; in one patient with splenic vessel preservation (SVP), the operating time was 210 minutes and blood loss was 650 ml, with a hospital stay of 6 days. In another patient without SVP, the operating time was 150 minutes and blood loss was 300 ml. The latter patient developed a 4-cm splenic infarct managed conservatively, and the hospital stay was 14 days. LapEn and LapSPDP are feasible and safe and achieved cure in patients with sporadic insulinoma and multiple insulinomas associated with MEN-1. However, the risk of pancreatic leakage after LapEn remains high, and LapSPDP without SVP may be associated with splenic infarct.

Laparoscopic approach for solitary insulinoma: a multicentre study

BACKGROUND

Surgical resection of insulinomas is the preferred treatment in order to avoid symptoms of hypoglycaemia. During the past years, advances in laparoscopic techniques have allowed surgeons to approach the pancreas and treat these lesions laparoscopically. We analysed the feasibility, safety, and outcome of patients undergoing laparoscopic resection of insulinomas in a large, retrospective, multicentre study.

METHODS

Thirty-six patients with pancreatic insulinomas were enrolled in this study. All patients were suspected of having solitary insulinomas after preoperative localisation tests and underwent a laparoscopic approach. Patients, operating characteristics and outcome were analysed.

RESULTS

Mean patient age was 48 years (range 20-77 years). Insulinomas were localised in the head (n=7), isthmus (n=2), body (n=14) or tail (n=13) of the pancreas before laparoscopic approach. Mean size of the lesions was 15.5 mm (range 4-25 mm). The surgical procedure was enucleation in 19 cases (52%), spleen-preserving distal pancreatectomy in 12 cases (33%), spleno-pancreatectomy in three cases (8%), one duodenopancreatectomy and one central pancreatectomy. Conversion rate was 30%. The reason for conversion in seven patients (63%) was the inability to localise the tumour during the laparoscopic procedure. In six of these cases laparoscopic ultrasonography was not performed. Mean operating time was 156 min (range 50-420 min). Postoperative course was uneventful in 23 patients (64%). Eleven patients (30%) developed specific complications of pancreatic surgery: intra-abdominal abscess (n=6) or pancreatico-cutaneous fistula (n=5). Mean duration of fistulae was 55 days (range 5-130 days) and all the fistulae were dry at follow-up. After a mean follow-up period of 26 months (range 2-87 months), 33 patients (91%) are free of symptoms, and three patients have been lost to follow-up.

CONCLUSION

The laparoscopic approach is safe to treat preoperatively localised insulinoma, with a morbidity rate comparable to that for the open approach. When the tumour is not found during laparoscopy, laparoscopic ultrasonography seems to be the most efficient tool to localise it and probably to prevent conversion.

Current concepts in functioning endocrine tumors of the pancreas

Duodenal and pancreatic endocrine tumors are uncommon and their surgical treatment is often difficult. The management of these tumors has changed with recent advancements in tumor localization, intraoperative hormone measurements, standardized surgical techniques, and a better understanding of the genetic basis of multiple endocrine neoplasia syndrome. We present our experience with 191 endocrine tumors and elaborate the contemporary management of functioning duodenopancreatic endocrine tumors.

[Pancreatic insulinomas: diagnosis and treatment]

BACKGROUND

Despite its rarity, the insulinoma is the most common pancreatic neuroendocrine tumor.

OBJECTIVE

Analyze clinical and immunohistochemical data from surgical resection of the pancreas insulinoma.

METHOD

Twelve cases are described, concerning surgical aspects, complications and medium-long term outcome of patients. They underwent surgical treatment due to clinical suspicion and biochemical diagnosis of hypoglycemia and hyperinsulinism.

RESULTS

The insulinoma was identified preoperatively in seven patients, while intraoperative ultrasonography and palpation were necessary for diagnosis in the other cases. Eight patients underwent pancreatic resection and pancreatic leak was observed in seven cases. Two patients developed diabetes mellitus and no mortality occurred in the current series.

CONCLUSION

All patients presented satisfactory outcome and remained asymptomatic with normal glicemia levels.

Preoperative detection of pancreatic insulinomas on multiphasic helical CT

OBJECTIVE

The objective was to analyze enhancement characteristics of insulinomas and to determine the ability of multiphase CT to localize these tumors.

MATERIALS AND METHODS

Prospective interpretations of multiphase helical CT scans were reviewed in 30 patients who had insulinomas resected over a 5-year period. CT scans were retrospectively reviewed to determine enhancement characteristics, tumor conspicuity in each phase of enhancement, and potential causes for false-negative findings.

RESULTS

Sixty-three percent (19/30) of tumors were identified on CT prospectively. An additional six tumors were visualized in retrospect, allowing characterization of 25 (83%) of 30 tumors. Most tumors were hyperdense on at least one phase (n = 19), three tumors were hypoattenuating, and three were isodense and pedunculated. Insulinomas were most conspicuous on the early phase in 15 patients and in the portal venous phase in three. All tumors that underwent pancreatic phase imaging were seen (13/13), whereas three of 18 arterial and six of 25 portal venous phase findings were inconclusive for tumor. In the six examinations with false-negative findings in which the tumor could be seen in retrospect, two tumors were isodense and pedunculated, three were in close proximity to vessels, and one had a cystic appearance.

CONCLUSION

Multiphasic CT has a moderate sensitivity in the detection of insulinomas. Most tumors are more conspicuous on the earlier phases of enhancement. The pancreatic phase may be more useful than the arterial phase. Potential sources of false-negative results include tumors adjacent to vessels, pedunculated morphology, or nonhyperattenuating lesions.

Minimally invasive endocrine surgery: laparoscopic resection of insulinomas

Pancreatic insulinomas are mostly benign and solitary tumors. Successful management of patients with insulinoma relies on accurate localization of the tumors and the use of appropriate surgical techniques. However, preoperative radiological imaging studies often fail to localize the insulinomas because of the small tumor sizes. Conventional intraoperative ultrasonography combined with palpation has been widely used as the best localization tool. Since contact ultrasonography, a new technique for localizing pancreatic lesions, became available as a laparoscopic study, several surgeons have utilized laparoscopy for not only localization but also resection of insulinomas. Previous reports of laparoscopic ultrasonography for intraoperative identification of insulinomas showed a 100% success rate in cases with insulinoma localized by preoperative imaging studies, but a less satisfactory rate in cases with occult insulinoma. Laparoscopic resection of insulinomas located in the head of the pancreas is often difficult because of its anatomical relationship with important adjacent structures such as pancreatic duct and mesenteric vessels. In contrast, insulinomas located in the body or tail of the pancreas are laparoscopically resectable even when they are in close proximity to the major pancreatic duct. Laparoscopic procedure is a feasible technique with low morbidity for surgical management of insulinomas. Accurate preoperative localization is essential for safe performance of this minimally invasive procedure.

Selective intra-arterial calcium stimulation with hepatic venous sampling for preoperative localization of insulinomas

OBJECTIVE

To determine the value of selective intra-arterial calcium stimulation with hepatic venous sampling using serum insulin and C-peptide gradients for the preoperative localization of insulinomas.

MATERIALS AND METHODS

Seven consecutive patients (three men and four women aged 15-77 (mean, 42.7) years) with hypoglycemia underwent selective intra-arterial calcium stimulation in conjunction with hepatic venous sampling. Insulin gradients were calculated by an individual blinded to all other preoperative imaging studies and operative findings. In all patients except one, C-peptide gradients were also analyzed. The results were compared with the preoperative findings of ultrasonography, computed tomography, arteriography and endoscopic ultrasonography, as well as with the intraoperative findings of ultrasonography and palpation at surgery.

RESULTS

Eight insulinomas (mean diameter, 12.5 mm) were diagnosed after surgery. In six patients, the calcium stimulation test with insulin gradients allowed accurate localization of the pathologic source of insulin secretion. Both C-peptide and insulin gradients substantially increased diagnostic accuracy. In one patient, C-peptide gradients were more helpful than insulin gradients for tumor localization.

CONCLUSION

Selective intra-arterial calcium stimulation with hepatic venous sampling is a highly accurate and safe method for the preoperative localization of insulinomas. Additional C-peptide gradients seem to be helpful in assessing tumor location, but further study is needed.

Recent advances in minimally invasive pancreatic surgery

For curative resection of pancreatic endocrine tumours, minimally invasive methods of pancreatic surgery, such as laparoscopy, should be indicated only for benign tumours. Among these uncommon tumours, pancreatic insulinomas are mostly benign and solitary. Successful management of patients with insulinomas relies on accurate localization of the tumour and the use of appropriate surgical techniques. Because of the small size of these tumours, conventional intraoperative ultrasonography combined with palpation has been widely regarded as the best localization procedure. Because contact ultrasonography, a new technique for localization of pancreatic lesions, can be used laparoscopically, several surgeons have used laparoscopy not only for localization, but also for resection of insulinomas. In the era of minimally invasive surgery for benign pancreatic lesions, we attempted laparoscopic-focused exploration of the pancreas for resecting insulinomas based on preoperative localization. We describe the use of this technique for the detection and resection of insulinomas and the results obtained, with a review of previous reports.

Laparoscopic ultrasonography for resection of insulinomas

BACKGROUND

There have been few reports on the use of laparoscopic ultrasonography as an aid for the resection of insulinomas. In this study, we review our experience with laparoscopic ultrasonography for the intraoperative localization and resection of insulinomas.

METHODS

We attempted laparoscopic resection of insulinomas in 7 patients (median age, 50 years) during a 4-year period. Preoperative imaging showed that 1 of the insulinomas was located in the head of the pancreas, 2 were located in the body, and 4 were located in the tail.

RESULTS

We identified the insulinomas in all 7 patients with laparoscopic ultrasonography. In 6 of the patients, the insulinomas were laparoscopically resectable, either by enucleation (4 patients) or by resection of the pancreatic tail (2 patients). Conversion to laparotomy was necessary for the insulinomas in the head of the pancreas because they were close to the portal vein and the major pancreatic duct. All patients showed improvement in their hypoglycemia after the operations. Minor leakage of pancreatic juice occurred in 4 patients, and this was resolved with conservative treatment.

CONCLUSIONS

Laparoscopic ultrasonography is useful for the intraoperative localization of insulinomas. Laparoscopy is a safe and feasible technique for resecting insulinomas located in the body or tail of the pancreas.

Assessment of selective arterial calcium stimulation and hepatic venous sampling to localize insulin-secreting tumours

OBJECTIVE

Non-invasive localization modalities such as ultrasound, computed tomography (CT) or magnetic resonance imaging (MRI) often fail to localize insulinomas smaller than 2 cm in diameter. Recent studies have shown that the selective arterial stimulation and hepatic venous sampling (ASVS) technique using intra-arterial calcium as the insulin secretagogue facilitates the regionalization of such occult insulinomas. This study assesses the sensitivity of ASVS in localizing insulin-secreting tumours.

SUBJECTS AND METHODS

Eleven consecutive patients (8 women), aged 29-82 years, were studied over the past 4 years at our hospital. Hyperinsulinaemic hypoglycaemia due to an insulin-secreting tumour was proven in all patients. Calcium gluconate (0.025 mEq/kg body weight) was injected directly into the arteries supplying the pancreas and the liver. Insulin levels were measured in samples taken from the right hepatic vein before and 30, 60 and 120 s after each injection. The ASVS technique was performed in all 11 patients; the results were compared with the surgical findings in 10 patients and the autopsy findings in 1 case. The ASVS results were also compared with the findings of other, previously performed imaging modalities.

RESULTS

ASVS correctly localized 4 insulin-secreting tumours to the head, 3 to the body, 1 to the tail, 2 to the tail or body of the pancreas and 1 to the liver. Thus, the sensitivity was 100% (11/11) whereas other localization techniques were less sensitive: 7/11 tumours were detected by angiography, 4/8 by endosonography, 3/8 by CT and 1/6 by MRI. Insulinomas (confirmed by histological examination), sized 4-25 mm, were found in 10 patients. All were cured by selective surgery and remained free of hypoglycaemia over the next 1-4 years of follow-up. An insulin-secreting neuroendocrine tumour in the liver was documented in 1 case at autopsy.

CONCLUSIONS

Arterial stimulation and hepatic venous sampling is a very sensitive technique for preoperative localization of insulin-producing tumours. It can help to plan minimally invasive surgery and to select an appropriate strategy for patients suffering from malignant tumours in others.

Laparoscopic pancreatic surgery in patients with neuroendocrine tumours: indications and limits

Laparoscopic pancreatic procedures are still at an evaluation stage with regard to their indications and techniques. Between January 1998 and December 2000, 13 patients with endocrine pancreatic tumours - 11 insulinomas and 2 non-functioning tumours-underwent laparoscopic surgery, laparoscopic ultrasonography being used in all the patients. Enucleation was performed in five patients. The operative time was 2-3 hours. Distal pancreatectomy was performed in six patients with insulinomas, and spleen preservation with intact splenic vessels was feasible in five. Splenectomy was necessary in one patient for technical reasons. Laparoscopic distal pancreatectomy with splenic vessel preservation was performed in two patients with a large (6 and 8 cm) non-functioning tumour. The mean operative time for all the patients undergoing distal pancreatectomy was 4 hours, ranging from 3 to 5 hours. A pancreatic fistula occurred in three patients after tumour enucleation and in two patients after distal pancreatectomy; the mean hospital stay for all patients was 5 days. Enucleation guided by laparoscopic ultrasonography thus allows safe tumour dissection and excision, laparoscopic distal pancreatectomy also being feasible and safe. Splenic salvage with splenic vessel preservation is technically possible. The laparoscopic approach allows a shorter hospital stay and an earlier return to normal activities.

Endoscopic ultrasound is highly accurate and directs management in patients with neuroendocrine tumors of the pancreas

Preoperative localization of pancreatic neuroendocrine tumors with traditional imaging fails in 40-60% of patients. Endoscopic ultrasound (EUS) is highly sensitive in the detection of these tumors. Previous reports included relatively few patients or required the collaboration of multiple centers. We report the results of EUS evaluation of 82 patients with pancreatic neuroendocrine tumors.

METHODS

We prospectively used EUS early in the diagnostic evaluation of patients with biochemical or clinical evidence of neuroendocrine tumors. Patients had surgical confirmation of tumor localization or clinical follow-up of >1 yr.

RESULTS

Eighty-two patients underwent 91 examinations (cases). Thirty patients had multiple endocrine neoplasia syndrome type 1. One hundred pancreatic tumors were visualized by EUS in 54 different patients. The remaining 28 patients had no pancreatic tumor or an extrapancreatic tumor. Surgical/pathological confirmation was obtained in 75 patients. The mean tumor diameter was 1.51 cm and 71% of the tumors were < or =2.0 cm in diameter. Of the 54 explorations with surgical confirmation of a pancreatic tumor, EUS correctly localized the tumor in 50 patients (93%). Twenty-nine insulinomas, 18 gastrinomas, as well as one glucagonoma, one carcinoid tumor, and one somatostatinoma were localized. The most common site for tumor localization was the pancreatic head (46 patients). Most tumors were hypoechoic, homogenous, and had distinct margins. EUS of the pancreas was correctly negative in 20 of 21 patients (specificity, 95%). EUS was more accurate than angiography with or without stimulation testing (secretin for gastrinoma, calcium for insulinoma), transcutaneous ultrasound, and CT in those patients undergoing further imaging procedures. EUS was not reliable in localizing extrapancreatic tumors.

CONCLUSIONS

In this series, the largest single center experience reported to date, EUS had an overall sensitivity and accuracy of 93% for pancreatic neuroendocrine tumors. Our results support the use of EUS as a primary diagnostic modality in the evaluation and management of patients with neuroendocrine tumors of the pancreas.

Laparoscopic detection and resection of insulinomas

BACKGROUND

Laparoscopic ultrasonography as a diagnostic tool for the localization of islet cell tumors has been described before, but few reports on laparoscopic resection of insulinomas exist. We retrospectively reviewed the results of our experience with laparoscopic detection and the resection of insulinomas to determine its feasibility.

METHODS

Between February 1996 and February 1999, 10 patients underwent operation for organic hyperinsulinism at our institution. Patient and clinical characteristics were studied retrospectively. Laparoscopic ultrasonography was performed to localize the insulinoma and then laparoscopic resection was performed.

RESULTS

Eight women and 2 men underwent operation for hyperinsulinism. In 6 patients the insulinoma could be resected laparoscopically, either by enucleation (5 patients) or by resection of the pancreatic tail (1 patient). Four procedures were converted to laparotomy for the proximate location of the insulinoma to the portal vein or pancreatic duct (3 procedures) and failure to identify the insulinoma (1 procedure). The overall success rate of preoperative localization of an insulinoma with the use of various imaging techniques was 60% (6/10 patients). Laparoscopic ultrasonography could identify an insulinoma in 90% of the patients (9/10 patients). The median hospital stay was 7 days.

CONCLUSIONS

Laparoscopic ultrasonography followed by laparoscopic removal of the insulinoma in patients with clinically manifested hyperinsulinism is a feasible and safe technique with low morbidity and fast postoperative recovery. Preoperative localization studies appear of limited value.

Lung flooding--a new method for complete lung sonography

A sonographic examination of the lung has so far been impossible because of sound reflection. In conjunction with video-assisted thoracoscopic surgery, lung sonography would be helpful to make up for the lack of direct palpation. Animal experiments with pigs were performed to find out whether lung sonography becomes possible following bronchoalveolar flooding with a suitable liquid. The lung was filled with whole electrolyte solution through the left leg of a double-lumen endotracheal tube after resorption atelectasis (method 1) or compressive atelectasis (method 2). As an alternative, liquid perfluorocarbon was used (method 3). Under atelectasis, the lung thus flooded was investigated by ultrasound applied transpleurally and endobronchially. The first results proved that lung flooding is possible if certain prerequisites are fulfilled. Perfluorocarbon flooding led to total sound absorption which prevented sonography, whereas flooding with whole electrolyte solution made complete lung sonography possible, making visible the intrapulmonary vessels, bronchi and peribronchial lymphatic nodes. Measurements proved that the unilateral flooding caused no significant changes in the arterial and central venous pressure nor in transcutaneous oxygen saturation.

Localization and surgical treatment of pancreatic insulinomas guided by intraoperative ultrasound

BACKGROUND

Approximately 20% to 60% of insulinomas cannot be localized preoperatively, and 10% to 20% cannot be found even during surgery. The operative complications associated with the blind surgical explorations are relatively high.

METHODS

Between January 1987 and December 1995, intraoperative ultrasound was used to localize insulinomas and guide surgical procedures in 28 patients.

RESULTS

Insulinomas were found by intraoperative systematic palpation in 24 patients (85.7%), while intraoperative ultrasound localized the tumors in 27 patients (96.4%). By the combination of these two techniques, all tumors were discovered. The surgical procedures were guided by intraoperative ultrasound. The operative complication rate was 14.3%.

CONCLUSION

Intraoperative ultrasound can accurately localize insulinoma, and delineate the spatial relationship between tumor and vital structures, such as pancreatic duct, common bile duct, and critical blood vessels. It can thereby help to increase the successful rate of surgery and avoid unnecessary blind pancreatectomy.

Insulinoma: a review of current management

Insulinomas are a relatively rare tumour which occur predominantly in the pancreas. The majority of the tumours are benign, but have profound effects upon the patient. The diagnosis of insulinoma is often elusive, and the management may involve demanding surgery with a significant morbidity. In this review article, all clinical aspects of insulinomas are examined. Particular emphasis is placed on the myriad modes of presentation, and the methods used to localise the tumour pre-operatively. Medical, as well as surgical treatments are discussed and their role in the management of both malignant and benign tumours. Despite potential difficulties encountered in managing patients with this tumour, a large majority may be either cured or achieve useful palliation.

Multiple insulinomas of the pancreas: a patient report

Whereas there is general agreement about the biochemical diagnosis of hyperinsulinism, the value of imaging to differentiate diffuse from focal pancreatic lesions is still a matter of debate. We describe a case of multiple adenomas of the pancreas in an eleven year-old boy. The source of hyperinsulinism was detected by pancreatic ultrasound examination and confirmed by MRI as a single adenoma of the pancreas. These radiological exams did not identify three other pancreatic adenomata. Our report outlines the difficulties in anatomically localizing the source of excessive insulin secretion in cases of hyperinsulinemic hypoglycemia.

Surgical management of gastrointestinal endocrine tumours

The surgical management of gastrointestinal endocrine tumours must involve a multidisciplinary approach. The importance of accurate diagnosis, rendering the patient safe, and, in our opinion, localizing the tumour(s) before embarking on surgery cannot be overemphasized. Surgery is the only available treatment for cure. Occult primary tumours are now rarely a problem with novel imaging techniques, which can also improve detection and hence clearance of local spread. Surgical management in extensive metastatic or multicentric disease is less rigidly defined, and is dependent on the endocrine syndrome. A better understanding of tumour pathology, for example in MEN 1, has not always simplified matters. An appreciation of the benefit of chemotherapy, use of somatostatin analogues and hepatic artery embolization are vital to target appropriate palliative surgery. Hepatic transplantation may have an increasing role in the future. Surgical strategies must adapt to new medical treatments. If therapeutically relevant, advances in tumour biology (for example somatostatin receptor subtypes and growth factors) will influence surgical strategies in the future.

Islet cell tumors of the pancreas

Pancreatic endocrine neoplasms are a heterogeneous group of tumors that produce active hormones and result in distinct clinical syndromes. For the most part, they are malignant and require sophisticated diagnostic and localization techniques in order to identify their presence. Delays in diagnosis are the rule rather than the exception. Improvements in the diagnosis of gastrinomas and insulinomas appear to result in an increase in resectability rates. The widespread availability of intraoperative ultrasonography, as well as improved knowledge of the location of these tumors, has also had an impact on improved cure rates. With heightened awareness of these syndromes, increasing numbers of patients can be identified and more effective treatments developed for the refractory and recurrent tumors.